Lock down compensator



Oct. 9, 1934. G. A. HALFVARSON LOCK DOWN COMPENSATOR 3 Sheets-Sheet l Filed Dec. 9, 1932 WITNESSESQ' I -7? 7 I I INVENTQR Gui/a 6 Hay/01:70;

AZORNEY Oct. 9, 1934. G. A. HALFVARSON LOCK DOWN COMPENSATOR Filed Dc.

9, 1932 3 Sheets-Sheet 2 INVENTOR 6 5/ If fb/fiarsan.

WITNESSES Eur W NEY 0a. 9, 1934. G. A. HALFVARSON 1,976,494

LOCK DOWN COMPENSATOR Patented Oct. 9, 1934 Gustaf A. Halfvarson, Chicago, 111;, assignor to Westinghouse Electri c Elevator Company, Chi,

cago, 111., a corpora tion of Illinois Application December il, 1932 Serial No. 646,364; 8 Claims. (oL 137-22) My invention pertains to cable idler sheaves and more specificallyit'relates "to elevator com pensator sheaves for guiding and restraining the compensating cables as the .elevator "car travels up and down the hatchway.

It is customary practice to provide modern elevator systems with compensating cablesth'e ends of which are attached to the and the counterweight respectively,

elevator car and the intermediate portions of which hang down to the bottom of the hatchway. As the car travels up the hatchway the Weight of the hoist cable betweenthe car and the hoist sheave decreases,

but the weight of the compensating cable hang ing below the car increases'at the .samerate, and the balance of the system is thus maintained.

By providing a sheave through compensating cables pass at the bottomf of the hatchway, the cables are guided and restrained in their movements, and by attaching-suitable weights to the sheave, the cables may be rior-.

mally tensioned a predetermined amount thereby improving the tractivefefiort of the hoist sheave on the hoist cables;

Difficulties have been experienced when abnormal conditions caused the safety"bral ing device to suddenly vgrip the guide rails and; retard the descent 'of either the'ca'r, orltheicojunterweight, and 'thenbody which was ascending continued to rise thereby, permittingfslack to develop in the hoist cables after which the ascending body fell. back :and [snapped the cables. Under such conditions the compensator sheave would also snap the cable's whengfalling back after being jerked up from the bottom of the hatchway. 7

Previous attempts to remedy these difiiculties by fastening the compensator, sheave down to the bottom of the hatchway have been unsatisfactory, since the total length ,of the cables in an elevator system does not remain constant but varies in accordance with changing conditionsof wear, loading and temperature. Hence,

when the cables were locked" down in such a 'manner as to make a rigid system abnormal detrimental stresses were setup. It is accordingly an object of-' my invention to provide a compensator sheave which normally moves freely in a-vertical direction but which yieldingly resists'excessive movement.

It is alsoan'object of'my invention -vide a self-adjusting elevator l to procompensator sheave which will guide and restrain the'move ments of the compensating cables vide" a compensating sheave which will float freely on the compensating cables within' 'predetermined vertical limits, but, which will deflnitely resist and limitju'pwa'rd motion beyond such limits. 1"

'A "further object of vide a compensating sheave which will permit thenormal expansion and contraction of the 'my inventionis to fpro fcables and prevent. the developmenaofQslack cable in the system: 'Ifhe invention itself; organization andits methodof operation, "toe 'gether 'with ,addit iona1' objects and advantages thereoflvwill best be understood from theiollowfing description'of a specific. embodiment, when drawings, in which: w .7

Figure .1 [is a side ..elevationa1 ,VieW I of my compensator sheavein assembled'relation with the associated guide rails; I y Fig; 2 is a front'elevational View thereof p FigL'3 isfa top plan viewi thereofj'and I Fig. "4 is a plan view of'the rail 'grippinfg'jawsd 'Referringmore specifically. tolthe drawings, the -compensator compr ses a. cable sheave 1 which hangs-in the lower loop of the compensat} ing. .CableS '2near the bottom of the hatchwayl As. shown in Fig. .2 ,i.:the hubrof the" sheave l is provided iwith roller" bearings 3'lsecured by retaining .rin'gs' l' [through which a stationary shaft 5 is disposed to support a weight frame'6 comprising a pair .of heavy side plates 6 joined togetherfby suitable bolts '7. Each side'plate 6" is provided with a bearing 8 for receiving one endof the shaft -5- arid a setscrew 9 for looking' the shaft stationarily therein. A grease fitting 11 is connected toa passageway l z which extends through the stationaryshaftb to lubricatethe bearings 3' on which thesheave rotates. Qabl'eiguard rods lfiextend between the side plates 6 adjacent the periphery of the cable ,s fie e' uide shoes 14 extend laterally from the side plates to cooperative engagement with a pair of Tguide rails 15 secured in the bottom of the hatchway in any suitable manner. Each guide shoe 14 may be provided with a Wear resistinglining 16. The sheave lis free torotate on itsroller bearings 3 within the weight ,frame 6;-which is restrainedfrom rotation-bythe vertical guide rails 15. v N

11 11 W h frame :bi up rt d on th sheave, tensions the cables 2;-continuously but permits H normal expansionand contraction of th cab e e a s h m r v ree i -e however, both as te ts v readin, connection with the accompanying which the v suitable screw bolts 22 and retaining plates 23.

Clamped to each guide rail 15 are rail gripping jaws '31 which are hinged together in pairs by a bolt 32 extending through openings; near the inner ends of the jaws, as shown in Figs. 3 and 4. Biasing springs 33 are compressed against intermediate portions'ofthe jaws 31 by a bolt 34 which extends loosely through an enlarged opening in each jaw. Each bolt 34 is threaded at one end and receives a nut 3i5 by which the tension of the springs 33 may be adjusted to provide a predeterminedresilient tension on the ,jaws. Although the jaws may be adjusted to rip the rails15 with; any desired pressure, I have found it preferable 'to apply "sufficient pressure to resist vertical; movement along the rail witha force of about one hundred pounds. 7 1 f 1' M- Apivotal bearing 37 is provided on the end of each rail gripping jaw adjacent the rail. From 1 each pivotal bearing 3'7 alink arm 38 is suspended having a roller 39- journall'ed 'inthe loweri'end thereofl asjshown in Fig. 1. A socket4l is also provided near the end of each jaw for. receiving a ifiber bumping plug 42, which maybe adjusted vertically by." suitable] screw bolts 4 3extending upwardly through the bottom of each orifice, as shown clearly in Fig. 1, A .lock nut .44 is provided on eachscrew bolt inorder that'a predetermined adjustment of the bumper plugs '42 may be permanently maintained. I

The rail. clamping jaws 31 are locked to the rails adjacent thegcom'pensating sheave at such a position that'their'inwardly projecting ends extend through an opening 45 in' the side plate 6' as shownin Figql. Each pair of suspended rollers 39 hangs adjacent opposite sides of the stem of the associated T-guide rail 15, andthe side plate 6' of the compensating sheave jis provided with a brakingfacecomprisinga' latf erally projecting inclined plane surface 46';ad jacenteach roller 39'to'force the latter against the rail stem when the sheave is liftedby the cables more than a predetermined amount; The pair; of inclined planes 46 adjacent each pair ofrollers, are disposed at a slightjangleito the vertical guide rail 15 in such a manner that they converge inwardly and downwardly, Sim+ ilarpairs of rollers and inclined planes are provided on each side of the sheave; i l

' when-the inclined surfaces 46 are-lifted more than a predetermined amount theyforce the rollers 39 into binding engagement with' the stem of the rail 15 thereby resisting the upward movement of the sheave. Even though therail clamping jaws -31 are adjusted to slip when a force of one hundred pounds is applied thereto, it will be understood that a much greater retarding force is applied-toloppose the upward movement of the sheave because of the binding action of the rollers 39 as they are wedged be tween the rail 15 and the inclined planes -46. To accentuate this eifect the engaging surfaces may be especially prepared in any suitable manner to increase the coefiicient of friction.-"For the faces of the inclined planes and'the rollers -I* have'found that hard smooth surfaces are exceed certain predetermined limits.

with-aroller -54 journalled at the lower end.

The guide channel 4'7 is so disposed on the side plate '6 relative to the roller 54 on the switch arm that the switch will be actuated when the vertical movements of the compensator sheave The switch 52 may be connected to interrupt the control circuits, actuate an alarm, or accomplish any other desired result, either when the compensator is; locked or. when the cables have stretched jex ce'ssivelyand allowed the compensator to drop down; 7,

To adjust mylock down compensating sheave forv proper operation; the "compression springs 33 on each pair of ra'il gripping jaws 31 are released sufficiently to permit sliding the jaws and rollers 39'down until thelatter are in proper locking position. 'In" this position each ,of the -four"'bumper plugs 42 is adjusted to obtaina clearance 'ofabout 2 /2 i ches at X; asshown in 'Fi'gg l. jThe'jaws are now. lifted until the bumper plugs 42iare nearly incontact with the'lower edges of the guide shoes 14 on the side plates 6! of the, compensator sheavejand the springs 33 are again compressed to clamp the jaws 31 to th r n c, It'jwill be apparent that when properly ad- 'justed, as above set 1 forth, my compensator sheaveis normally free to move up and down a 3111 predetermined distance, but when'i'tis lifted slightlyjmore tharra predetermined distance the rollers 39 are"we'dged;between the converging plane surfaces 46 and the rail '15 thereby gripping the latter with a force; which prevents further upward movement of the compensator." I, When .,the' sheave'and' its weightframe are lowered bv expansion or stretching of the compensating cables", the bumper plugs 42 are en- 'g'aged by the lower edges of the guidesl iz'ies 14 H jon the side plates. Since the weight of the compensating sheave structure is much greater than the slippage resistance of the jaws 31, on the rails, the] jaws are caused jto slide downwardly on the rails thereby automatically maintaining 1;.

the proper adjustment. The compensating sheave being thus I automatically readjusted for cable stretching will always permit free vertical movement of. the sheave through a predeterapplied. ff v It-will be seen that I. have provided a simple, compact, rugged compensator which continuousmined distance before the retarding force is L ly applies'a predetermined tensioning force to g the compensating cables while permitting free vertical movement througha constant distance which is notmodified by the cables stretching .or expanding, and which applies a predetermined resisting forcewhen the compensator sheave is lifted up more'thana predetermined distance.

Although I have shownand', described a spereceiving sheave, a weight frame supported by.

stricted except as necessitated by the prior art and the scope of the appended claims.

I claim as my invention:

1. The combination with an elevator system comprising an elevator car, a counterweight, and an interconnected compensating cable, of a sheave hanging in the loop of said compensating cable, a frame supported by said sheave, braking means associated therewith to apply a retarding force thereto when said sheave has been lifted a predetermined distance, and means for supporting the braking means independently of said frame to control said predetermined distance.

2. The combination with an elevator system comprising an elevator car, a counterweight, and an interconnected compensating cable, of a sheave hanging in the loop of said compensating cable, a frame supported by said sheave, braking means associated therewith to apply a retarding force thereto when said sheave has been lifted a predetermined distance, means for supporting the braking means independently of said frame, and means for automatically readjusting said distance when the sheave is lowered whereby said distance is maintained constant irrespective of wearing or stretching of the compensating cable.

3. A device for tensioning and guiding elevator compensating cables comprising a cable receiving sheave, a weight frame supported thereon, vertical guide rails for guiding the movements of said frame, means for applying a braking force to retard upward movement of said frame comprising rail clamping jaws, rollers suspended therefrom, and means carried by said frame to engage said rollers when the frame moves upwardly.

4. A device for tensioning and guiding elevator compensating cables comprising a cable receiving sheave, a weight frame comprising a pair of side plates secured together in enclosing relation around said sheave, a shaft extending freely through said sheave, means for securing the ends of said shaft stationarily in the side plates, vertical guide rails, guide shoes on said side plates extending in operable relation to said guide rails, resilient clamping means secured to each guide rail, braking elements associated therewith, and means on said side plates for engaging said braking elements to apply a predetermined braking force to said side plates when they are lifted by the cable.

5. A device for tensioning and guiding elevator compensating cables comprising a cable said sheave, vertical guide rails for guiding the weight frame, a plurality of braking elements, means movably mounted on the guide rails for supporting said braking elements, means on the weight frame for positioning the braking elements and their supporting means within predetermined limits in accordance with the position of the frame, and means on said frame for engaging the braking elements to apply a braking force to the frame when it is lifted by the cables.

6. A device for tensioning and guiding elevator compensating cables comprising a cable receiving sheave, a weight frame supported by said sheave, vertical guide rails for guiding the weight frame, a plurality of braking elements, friction clamping means disposed on the guide rails for supporting said braking elements, means responsive to downward movement of the frame for moving the friction clamping means downwardly on the guide rails, and means on said frame for causing the braking elements to apply a braking force to the frame when it is lifted by the cables.

7. A device for tensioning and guiding elevator compensating, cables comprising a cable receiving sheave, a weight frame supported by said sheave, vertical guide rails for guiding the weight frame, a plurality of braking elements, means for supporting the braking members, means for movably clamping the supporting means to the guide rails with a predetermined pressure, means responsive to a predetermined downward movement of the frame for moving the supporting means downwardly, and means on said frame for engaging the braking elements to apply a braking force to the frame when it is lifted beyond a predetermined distance by the cables.

8. A device for tensioning and guiding elevator compensating cables comprising a cable receivingv sheave, a weight frame supported by said sheave, vertical guide rails for guiding the weight frame, braking faces on said frame, braking elements disposed to be wedged between the braking faces and the guide rails to provide a braking effect on the frame upon upward movement of the cables, and means for supporting the braking elements a predetermined distance out of engagement with said braking faces to permit a predetermined upward movement of the cables before bringing the braking effect into action.

GUSTAF A. HALFVARSON. 

